Reducing engine emissions

ABSTRACT

At part-throttle accelerations, ignition timing of sparkignition engine is sharply retarded for at least a few seconds to reduce hydrocarbon and nitrogen oxide emissions from exhaust. Retarding can be made responsive to throttle-opening movement or acceleration inertia of rotating part of engine. Fluid-flow and electric-heating arrangements are shown for determining the length of the retard period.

United States Patent Marsee Mar. 7, 1972 [54] REDUCING ENGINE EMISSIONS2,732,833 1/l956 Hook ..123/117 2,825,320 3/1958 Brueder... .....123/117[72] I Mend 2,864,356 12/1958 Udale ..123/117 [73] Assignee: EthylCorporation, New York, N.Y. 3,157,168 11/1964 Sterner et a1. ..123/1173,272,191 9/1966 Walker et a1. ..123/117 [22] 3,431,897 3/1969 Eltinge..123/1 17 [211 App]. No.: 857,255 3,472,213 10/1969 Walker ..123/1173,476,094 11/1969 Rucins et a1. ..123/117 Related US. Application Data[63] Continuation-impart of Ser. N0. 611,346, Jan. 24, Primary 1967,abandoned. Attorney-Donald L. Johnson [52] US. Cl. 123/117 A, 123/117 RABSTRACT [51] lnLCl 02p5/04 At part-throttle acceleratlons, 1gn1t1ont1m1ng of spark-1gn1t1on [58] Field ofSearch ..123/117. 1,117,146.5Cengineis Sharply retarded for atleastafew Seconds to reduce [56] Reta"Cned hydrocarbon and nitrogen oxide emissions from exhaust. Re-

my tarding can be made responsive to throttle-opening movement UNITEDSTATES PATENTS or acceleration inertia of rotating part of engine.Fluid-flow and electric-heating arrangements are shown for determining2,336,424 12/1943 Schachenman; ..123/1 17 the length f h retard perimi2,621,641 12/1952 Sterner 123/1 17 2,650,581 9/1953 Short et a1. ..123/117 11 Claims, 19 Drawing Figures 10\ 2 LV .12 1 l d 74 12277,, 1 122 mYEIIC 75 102 3 15 1 a iff r e 114 112 42 Art-elevation- 799.57 0/15/19Pressure- 7'? film/1 in; Fame 0 106 64 38 71 M 58 T 7 2 Open 24 33 34 TO0 50 FATENTEDHAR SHEET1UF4 70 Includes 123 Centrifugal 7'0 Ad Vance ma75 10 f 0r 0M9) AcceZerati on- 470/! s/ve Pressure- To Tizmiile 2gVacuum Adi/(awe IIIIIIIII PATENTEDMAR 7 I972 SHEET 2 BF 4 99 mm Z WC e am M Throttle To Suction PATENTEDMAR 7 I972 v 3,646,921

sum 3 BF 4 PAIENTED'MAR 11912 SHEET l 0F 4 REDUCING ENGINE EMISSIONSThis application is a continuation-in-part of application, Ser. No.611,346 filed Jan. 24, 1967 and subsequently abandoned.

The present invention relates to spark-ignition engines such as thoseused to power automobiles.

Among the objects of the present invention is the provision of novelignition timing arrangements for such engines.

Another object of the present invention is to reduce the emission ofundesirable materials in the exhaust of spark-ignition engines.

The foregoing as well as additional objects of the present inventionwill be more fully understood from the following description of severalof its exemplifications, reference beingmade to the accompanyingdrawings wherein;

FIG. 1 is a somewhat schematic illustration with parts in section, ofone embodiment of ignition-timing arrangement representative of thepresent invention;

FIG. 2 is a view similar to that of FIG. 1 showing another embodiment ofthe present invention;

FIG. 3 is a broken-away vertical sectional view of a somewhat differenttype of ignition-timing arrangement representative of the presentinvention;

FIG. 4 is a horizontal sectional view of the construction of FIG. 3taken along lines 44;

FIG. 4A is a view similar to FIG. 4 of a modified construction;

FIG. 5 is a partially sectioned and partially cutaway elevational viewofa further embodiment of the present invention;

FIG. 6 is a side view of the construction of FIG. 5;

FIGS. 7A through 7E show stages in the operation of the construction ofFIGS. 5 and 6; and

FIGS. 8 through 14 illustrate other embodiments of the invention.

It has been discovered that spark ignition engines which during mildaccelerations have their ignition temporarily sharply retarded for a fewseconds, make out much better in smog-emission tests yet do notsacrifice performance characteristics to any significant degree. Only afew to 30 seconds of retarding is needed but the retarding should besharp, as for example to substantially completely offset the vacuumadvance, or to be at least about 10 and preferably with respect to thepart-throttle cruise timing advance that would be provided by acombination of centrifugal and manifold vacuum advance mechanisms. Thecentrifugal advance is solely dependent on engine speed and normallyadvances the timing as this speed increases. The vacuum advance respondsto variations in engine vacuum and normally increases the advance as themanifold pressure drops.

When initiating full throttle accelerations as well as those near fullthrottle, the manifold pressure will normally increase sharply and causethe vacuum advance mechanism to drop back some from fully advancedposition. However, for minor accelerations the manifold pressure willgenerally not increase enough to drop the timing as much as about 5 frommaximum advance for the particular engine speed. Such small retarding isnot of much effect in reducing the emission of undesirable exhaustproducts.

A feature of the present invention is the provision of means responsivedirectly to acceleration or to an acceleration control to effect theforegoing ignition retarding.

The retarding of the invention can be readily accomplished by entirelyor substantially entirely offsetting or eliminating the vacuum advanceinasmuch as such advance is normally at least about 15 at cruise. It ispreferred for the retarding to be initiated somewhat gradually andterminated aomewhat gradually, to avoid abrupt changes in torque.Bleeding air into the vacuum that causes the vacuum advance convenientlyaccomplishes this type of gradual operation, particularly when thebleeding takes place via an elongated line having an internal diameterabout the same size as that of the line that applies suction from theintake manifold to the vacuum advance mechanism. Internal diametersofone-eighth inch with a bleed line at least about 6 inches long make avery suitable combination, the ignition retarding then taking a fractionof a second to reach maximum retard after bleed valve at the remote endof the bleed line is suddenly opened. Similarly the retarding tapers offto full advance over a fraction of a second when the bleed valve issuddenly closed.

The acceleration-responsive means for effecting the ignition retard ofthe present invention can be connected for mechanical operation directlyby the throttle control of the engine, or it can be arranged foroperation by the inertia effects of a rotating portion of the engine.The throttle control connection is also conveniently arranged toadditionally retard ignition when the engine is idling, to furtherreduce the emission of undesirables from the exhaust.

As used herein, accelerations refer only to increases in speed, and notto decreases.

Turning now to the drawings, FIG. 1 shows an ignition-timing arrangementhaving an acceleration-responsive means 10 connected to the conventionalvacuum advance mechanism 12 that includes a diaphragm head 14 responsiveto the manifold pressure for advancing the breaker plate (not shown) inthe distributor 16. Instead of having the diaphragm head connected tothe intake manifold, it can alternatively be connected to the carburetorthroat downstream of the throt tle. Acceleration-responsive means 10 ismechanically connected to the throttle control by a rod 20 that is movedin the direction of arrow 22 when the throttle is opened. Rod 20 rotatesa cam 24 which is pivotally mounted by shaft 26 on a block 28 that canbe in turn secured to a fixed position on the engine. Cam 24 is rigidlyconnected to a shaft 26 which also rigidly carries an arm 30 directlyoperated by rod 20.

A cam-follower plate 32 is held against the bottom of cam 24 and isarranged for pivoting around pin 34 rotatably held on another fixedsupport 36. Integral with plate 32 and extending upwardly are twoactuating fingers 38, 40, shown as engaging plungers 42, 44respectively. Plunger 44 is a valve needle which cooperates with a valveseat 46 in a valve block 48 but is urged outwardly away from that seatby spring 50. This outward urging causes the plunger 44 to pushoutwardly against finger 40 and thereby hold cam-follower plate 32against cam 24. Plunger 44 is shown as guided in its movement by havingits shank 52 slidably fitted in a cylindrical socket 54 in block 48 andcan also be provided with an O-ring seal 56 to control the flow of bleedair.

The shank of plunger 44 is reduced at 48 to provide a passagewaycommunicating between the valve seat at the bottom of socket S4 and aport 60 that opens into an air inlet chamber 62. An air filter 64permits filtered air to freely enter the chamber 62 from the outside.

Plunger '42 has secured to its inner end a diaphragm 70 which can beclamped between two cup washers 71, 72 carried by the plunger. Diaphragm70 is also clamped between a head cover 74 and body 76 of a pneumatic orhydraulic pump assembly to define a pump compartment 78 and a ventcompartment 80 on opposite sides of the diaphragm. Vent compartment 80is open to the atmosphere as by means of perforated plug 82, while pumpcompartment 78 communicates through passageway 84 with an actuatingchamber 86 of a second bleed valve 88. Valve 88 is urged against itsseat 90 by a spring 92 and this valve is also secured to a diaphragm 94that closes the actuating chamber 86. A cavity 96 on the other side ofdiaphragm 94 is opened to the atmosphere by means of vent 98.

Pump compartment 78 also has a vent connection but of limited character.This vent connection is established through a longitudinal opening 100drilled through the bottom of plunger 42 and leading into the interiorof the plunger which itself is hollow and has vent perforations 102, 104in its walls. Inside the plungers hollow interior, which is wider thanopening 100, is fitted a movable valve seat 106 urged towards theshoulder 108 at the inner end of opening 100, by a spring 110. Valveseat 106 also has a longitudinal passageway 112, the outer mouth ofwhich is adjacent a ball check 114 held in place in opening 100 as bymeans of a retainer bar 1-16. The

outer mouth of passageway 112 is arranged to form an imperfect seat forthe ball check 116 so that air or other fluid can leak from pumpcompartment 78 past the ball check through passageway 112, the hollowinterior of plunger 42, vent perforations 104, vent compartment 80, andfrom there to the atmosphere. The imperfect seating of ball check 116 isreadily arranged as by punching a very small groove across the face ofthe seat in one or more locations. Movable valve seat 106 is alsoarranged to seat against shoulder 108 to provide another airtight oralmost airtight closure.

The two bleed valves '44 and 88 are connected in parallel between theatmosphere and a bleed passageway 118 in valve block 48 which in turncommunicates through bleed tube 120 to the suction line 122 of thevacuum advance mechanism.

The apparatus of FIG. 1 is shown in the position it occupies when theengines throttle is at its idle stop. Plunger valve 44 is held open byspring 50 and the second bleed valve 88 is held closed by spring 92. Airaccordingly bleeds from chamber 62 through port 60 past valve seat 46and into suction line 122 so that the pressure in that suction line andin diaphragm head 14 is fairly close to atmospheric. The vacuum advanceis accordingly in its retarded position and the ignition is timed about15 crankshaft degrees later than it would be if the vacuum advance werein full advance position. Vacuum advance mechanisms generally cause theadvancing of the ignition timing to begin when the pressure in diaphragmhead 14 is at least a few inches of mercury below atmospheric so thatthe mechanism will provide no advance as long as the bleeding of theacceleration-responsive means is effective to keep the pressure insuction line 122 above that level.

Every time there is an opening movement in the throttle of the engineoperated in accordance with FIG. 1, fingers 38 and 40 move toward theleft. Finger 40 is made quite springy and yieldable so that it onlyeffects closing of plunger valve 44 when the engine throttle begins tomove away from idle position. Further movement of the throttle away fromidle position will merely cause finger 40 to yield while finger 38,which is much more rigid, will continue to move toward the left. Anymovement of finger 38 towards the left causes plunger 42 to move towardthe left, increasing the pressure in pump compartment 78. This increasein pressure causes ball check 114 to seat against the mouth ofpassageway 112 and also pumps additional fluid into actuating chamber86, thus pushing diaphragm 94 to the right and unseating bleed valve 88.This also causes the loss of vacuum advance and a consequent 15 delay inignition timing.

After a throttle-opening movement is completed the pressure increasethereby caused in pump compartment 78 begins to drop off as fluid bleedspast the imperfect seat between ball check 114 and the outer mouth ofpassageway 112 in the movable seat 106. A few seconds is all that isneeded for this pressure to drop enough to permit bleed valve 88 to bereseated by its spring 92. This reseating terminates the bleed of airinto suction line 122 and the normal vacuum advance is thereby restored.

Movements of the throttle in throttle-closing direction cause thediaphragm 70 to move to the right, reducing the pressure in pumpcompartment 78 and permitting fluid to move through passageway 100 fromvent compartment 80 pushing the ball check away from the outer mouth ofthe passageway. The acceleratiomresponsive means is accordingly ready atall times to respond to any acceleration.

FIG. 2 shows an acceleration-responsive mechanism 210 basically similarto that of mechanism of FIG. 1 but without the idle bleed arrangementand with a modified control connection. Apparatus 210 has a bleed line220 that opens into a bleed port 259 normally held closed by valve 288which is actuated by diaphragm 294, which in turn is operated from pumpcompartment 278 through a passageway 284, as in the similarly numberedparts of the construction of FIG. 1. Plunger 242, which is arranged todo the pumping, is engaged by finger 238 which in turn is controlled bycam 224 which is moved in the direction of arrow 222 when the throttleof the engine is being opened. Cam 224 has an operating ramp 225 that isengaged by a follower nose 223 secured to an extension of finger 238.Ramp 225 is shown as shaped so as to have relatively small movements offinger 238 when the engine's throttle is opened at near idle position,but relatively large movements when the throttle is moved towards openposition from positions closer to full open. In this way the ignitionretarding of the present invention can have a longer duration at thehigher speeds where acceleration is less pronounced than at the lowerspeeds. At the lower speeds, for example, the retarding interval can beas little as 2 seconds and at the higher speeds as much as 4 seconds.

FIGS. 3 and 4 illustrate a modification of the invention in which theacceleration-responsive means is built into a distributor assembly. Thelower portion of such an assembly is shown at 300 with the distributorshaft 302 having a longitudinally extending air passageway 304, thelower end of which is connected by rotating seals 306, 306 to a bleedtube 320. The upper end of passageway 304 extends through a radiallydirected arm 308 where it terminates in a check chamber 309 that isclosed by a ball check 311 that covers a vent port 319. A spring 315biases the ball check against the port and in this way closes thepassageway 304.

Radial arm 308 is rigidly secured to distributor shaft 302 so as to turnwith it. Rotatably mounted with respect to the shaft is an inertia arm317 which is rotated by radial arm 308 acting through a compressionspring 313. The direction of rotation of distributor shaft 302 isindicated by the arrow 321 in FIG. 4, and spring 313 is arranged so thatany acceleration of the engine causes this spring to be compressed bythe inertia of inertia arm 317. When the acceleration is completed thisspring will extend itself again and return the inertia arm to normalposition with respect to radial arm 308.

An unseating pin 323 carried by inertia arm 317 is arranged to penetratethrough vent port 319 and pushball check 311 away from its seatingengagement whenever the inertia arm is moved close to the radial arm. Asa result every acceleration of sufficient magnitude to cause unseatingof the ball check will also cause venting of the vacuum advance unit andretarding of the ignition. Such retarding will continue throughout anentire acceleration.

FIGS. 5 and 6 illustrate a construction in which the vacuum bleed iselectrically timed. These figures show a throttle valve 421 in acarburetor throat 427 affixed to and rotatable on a shaft 429 thatcarries an electrically nonconductive throttle arm 430. Link 420 havingan end 431 bent over and inserted through an aperture 433 in arm 430connects that arm to a throttle pedal of an automobile for example, sothat movement of the throttle pedal will move link 420 in the directionof the arrow 434 to cause the throttle valve 421 to move toward fullyopen position. correspondingly, moving the throttle pedal in theopposite direction will move the throttle valve toward closed position,and this motion can be assisted as by a return spring.

The throttle arm 430 can be molded of plastic with the molding providingthe aperture 433, and also providing an integral ear 435. On this car ismounted one end of a bimetallic temperature-responsive strip 437 as bymeans of a rivet 439 which also secures an electrical lead 441 to thestrip. The other end 443 of the bimetallic strip coacts with the stem445 of a poppet valve 447 the head of which is biased as by spring 449against a seat 451 carried by a floating cylinder 453 of a bleed controlassembly 455. The cylinder is secured to a housing 457 of the bleedcontrol assembly by a flexible diaphragm 459, the outer margin 461 ofwhich is thickened and clamped against a shoulder 463 of the housing, bymeans of a mounting plate 465 loosely fitted around valve stem 445 andheld in place by a snapring 467. The central edge of the diaphragm canbe vulcanized directly to an external shoulder 477 at the valve end ofcylinder 453.

A suction connection 469 opens into the interior of the housing 457 andreceives a suction line such as that shown at (FIG. 1) connected to thevacuum advance system of the distributor. Cylinder 453 is hollow and itsinterior is in open connection with the suction connection 469, althoughthe open end of the cylinder can be partially obstructed as by a bar 473against which spring 449 is compressed. The diaphragm may permit thecylinder to move so far inwardly that its open end engages a wall of thehousing 457 or of the suction connection 469, but in that event thecylinder end can have a cutout or the like so that such engagement doesnot obstruct the flow of air between suction connection 469 and thespace 475 around the cylinder. Another spring 481 is positioned in thisspace and arranged to bias cylinder 453 toward mounting plate 465.

Poppet valve 447 has at least its stern 445 of electrically conductivematerial, and to this stem is connected as by clamp 483, an electricallead 485. Valve 447 also has a nose 487 that projects internally of thecylinder 453 and comes close to but is spaced from bar 473 when thevalve is in its seated position.

The bleed control assembly 455 is carried by a pivot arm 489 to whichhousing 457 may be welded, and the arm in turn is frictionally held by apivot screw 491 against a fixed surface 493. A friction pad 495 betweenthe pivot arm and the surface 493 is engaged by both of these membersunder the influence of a cupped spring washer 497 around the screw 491where it is held in place by a nut 499.

The construction of FIGS. 5 and 6 operates by connecting leads 441 and485 to a source of electric current such as a battery of an automobilehaving an engine equipped with a carburetor so modified. FIG. 7A showsthe condition of the vacuum bleed assembly when the engine is notrunning and the throttle is closed. Throttle valve 421 is in idleposition and bent over end 431 of throttle link 420 engages an abutment403 on pivot arm 489 to hold the bleed assembly in the illustratedposition. This position corresponds to the extreme limit of theclockwise rotation of the assembly around pivot screw 491. In thisposition valve 447 is held against its seat by spring 449, and the seatend of the cylinder 453 is held against mounting plate 465 by spring481. This arrangement holds valve stem 445 in its extreme left-handposition where it still falls short of engaging the bimetallic strip437. When the engine is started and is running just above idle, theapparatus takes the position illustrated in FIG. 6. In this positionintake manifold suction is applied through connector 469 to space 475and causes the diaphragm 459 to flex to the right carrying cylinder 453and valve 447 with it. The shank of the valve is still out of contactwith bimetallic strip 437 even though that strip has been pivoted withthe throttle to the off-idle position.

Should the throttle now be opened a little further, then bimetallicstrip will engage the valve stem 445 and then push the shank to theright unseating the valve, as illustrated in FIG. 7B. Air is thusadmitted into the suction chamber and causes the ignition to be retardedas in the construction of FIG. 1. As a result the pressure in space 475increases and diaphragm 459 is moved to the left carrying cylinder 453with it. Bar.473 at the interior end of the cylinder engages valve nose487 as the cylinder moves toward the left, and causes the valve stem topress against bimetallic strip 437. The friction of the pivot arm 489 isadjusted to be low enough so that instead of the valve stem pushing thebimetallic strip to the left under the above pressure, the assembly 455is pivoted to the right or counterclockwise. The assembly thus reachesthe position illustrated in FIG. 7C. Arrows 407 show the amount of tiltwhich the assembly has undergone.

The above shift in the assembly takes place fairly rapidly, and isaccompanied by a flow of electric current through the bimetallic stripas a result of its contact with the valve stem. This current heats upthe bimetallic strip and after a few seconds causes it to deflect awayfrom the valve seat. The deflection proceeds more than enough to permitthe valve to reseat itself, and thus breaks the electrical connectionbetween the strip and the valve stem. The assembly is now in theposition illustrated in FIG. 7D.

The reseating permits intake manifold suction to be reestablished inspace 475 causing diaphragm 459 to be pulled toward the right carryingthe cylinder and valve with it. At the same time the breaking of theelectrical connection stops the heating of the bimetallic strip andpermits that strip to unflcx. The combined result is to bring theapparatus into the position shown in FIG. 75. In this position theassembly is ready for the next acceleration with the free end of thebimetallic strip close to but just out of contact with valve stem 445.Additional accelerations will cause the assembly to go through the samekind of cycle, each acceleration carrying the assembly a little furthercounterclockwise around pivot screw 491. Closing movements of thethrottle will cause bentover end 431 of throttle link 420 to rotate theassembly clockwise as the throttle valve moves towards closed position,thus keeping the parts of the apparatus so related that it is alwaysready for the next acceleration.

The bimetallic strip 437 and the electric supply to it are arranged tocause the strip to undergo its maximum deflection as in FIG. 7D about 2to 4 seconds after the current flow starts, so that the ignitionretarding action is completed within such time period. The strip can berelatively insensitive to small temperature changes so that it is notdeflected by variations in ambient temperatures such as between summerand winter and between hot and cold conditions of the engine. Theheating current can thus be arranged to heat the strip to I50 C. orhigher in order to effect the desired deflection. The engaging surfacesof strip 437 and shank 435 can be of good electrical contact materialsuch as silver, in order to have a long life in use.

The delay feature used in the construction of FIG. 1, for example, toextend the retarding for a few seconds after the throttle begins thethrottle-opening movement, can be effected by other forms of dashpots,such as a hydraulic dashpot that can be conveniently operated withgasoline as the liquid, by linking the dashpot to the carburetor bowl.

A construction of this type is shown in FIG. 8 which illustrates theapparatus of FIG. 1 modified to have chamber opening into the fuel bowl15 of a carburetor so that thischamber as well as chambers 78, 86 andpassageway 84 (see FIG. 1) are filled with gasoline at all times. Theoperation of FIG. 8 corresponds to that of FIG. 1.

Electrically or mechanically operated delays can also be used such as byhaving a throttle-opening movement close an electric switch that heatsup a catch which is released after the heating is maintained for a fewseconds. FIG. 9 illustrates a construction of this type in which acontrol assembly 555 is mounted on a pivot arm 589 frictionally held inthe same way as arm 489 of the construction of FIG. 6. A rotating arm537 mounted for rotation with the throttle valve, as in FIG. 6, bends aswitch blade 5ll carried by pivot arm 589 into con tact engagement witha contact blade 513, and into latching engagement with a bimetalliccatch 515.

Catch 515 is surrounded by a heating coil 517 which is energized by acircuit closed by the contacts. The circuit also in cludes a solenoid519 with an armature 521 that when actuated lifts a flapper valve 523from the vacuum advance line and also pushes against the actuating arm537 to rotate the assembly 555 around its pivot. After a few seconds ofelectric current flow the catch is heated enough to deflect it out ofthe way and permit switch blade to move away from control blade 513breaking the electrical current. Blade 511 and flapper valve 523 arebiased to their illustrated positions so that the assembly then restoresthe suction in the vacuum advance mechanism. The operation of thisconstruction is accordingly similar to that of FIG. 6.

Other forms of delay include the pneumatic type which is based on theresistance to the rotation of a rapidly rotated air vane, as inspring-wound music box movements. Thus the opening movement of thethrottle can wind a spring for rotating the vane, and the ignitionretard effected for the time needed by the vane to run down the spring.An arrangement of this type is illustrated in FIG. 10 where a throttlearm 637 is connected by a spring 640 to a rack 642 that has a row ofgear teeth 644 meshed with the teeth of a drive gear 646 that isrotatably mounted on a frame 648. Gear 646 has a one-way driveconnection with a set of speed-increasing gears 651, 652, 653, 654, thelast being on a stem that also carries a vane 660. Frame 648 is heldbetween guides 661 and 662 that allow for limited motion toward thethrottle arm 637. A link 666 is connected between frame 648 and a flapvalve 668 on suction conduit 669 which valve is biased as by a springtoward a position closing the open end of that conduit. An additionalstop 674 can be provided to limit the opening of the flap valve 668.Rack 642 is held on frame 648 as by a guide pin 675 fixed to the frameand received in a guide slot 676 extending along the length of the rack.A return spring 678 substantially lighter than the spring 640 urges therack 642 in a direction away from the throttle arm 637.

When the throttle arm 637 of the construction of FIG. 10 is moved inthrottle-opening direction it stretches spring 640 and thus applies anupward force to rack 642 which in turn starts to rotate drive gear 646.In this direction of rotation gear 646 is engaged with vane 660, so thatits rotation is considerably slowed as a result of the air resistanceagainst rotation of the vane. Rack 642, urged upwardly by stretchedspring 640, accordingly lifts frame 648 and with it the flap valve 668.The suction conduit 669 is in this way opened to the air, sharplyreducing the suction as well as the ignition advance as in theconstructions of the previous figures. The flap valve remains lifteduntil the vane 660 has rotated enough to permit rack 642 to relax spring640. Return spring 672 thereupon pulls the fiap valve down into positionclosing suction conduit .669 and also lowering frame 648. Furtheropening movements of the throttle will cause repetitions of the aboveignition retarding action.

Closing movements of the throttle carry throttle arm 637 closer to frame648 permitting spring 678 to pull the rack 642 back so that it is readyfor the next throttle opening movement. During the backward travel ofthe rack it is still meshed with one-way drive gear 646 but this gearturns easily in the direction that brings the rack down, without dn'vingvane 660.

An inertia delay can also be used, as by similarly winding a spring thatis connected to rotate a relatively heavy weight. The weight can be soarranged that it takes a few seconds for the weight to rotatesufficiently to cause the spring to unwind. Such an arrangement isprovided by replacing vane 648 in the construction of FIG. 10 by a wheelwith a heavy rim. The inertia of such wheel as it is subjected to theinfluence of the speed increasing gear drive provides a delaying effectsimilar to that of the air resistance against the vane 660.

It will be noted that with the type of construction illustrated in FIGS.3 and 4, or in any other arrangement which causes the ignition retard'ofthe present invention in response to the inertia effects of theacceleration to be responded to, no delay is needed to extend theduration of the retard. It may, however, be helpful in such arrangementsto terminate the ignition retard before the acceleration terminates, asby providing a time control valve inserted in bleed tube 320 to shutdown the bleed after a few seconds of retarding have been completed.Alternatively the housing for the distributor of FIG. 3 can be madealmost completely airtight so that it provides an air reservoir oflimited capacity. Accordingly when a vacuum bleed is effected thelimited amount of air within the housing will limit the duration of thevacuum drop. When the air within the housing is bled into the vacuumline sufficiently the pressure within the housing will be effectivelyreduced to that normally in the vacuum line and the ignition retard thusterminated. Air will gradually leak into the housing from the exteriorso that after the bleed opening is closed, the equipment will soon beready for the next mild acceleration.

The actuation of the ignition retarding of the present invention can beprovided by other arrangements, as by the acceleration pump which isconventionally used in carburetors. The hydraulic pressure developedwhen the pump is operated can be very simply arranged to push open thebleed valve of FIG. 8, for instance. Such a construction is illustratedin FIG. 11.

In FIG. 11 a carburetor 701 has an acceleration pump 703 I connected byoutlet passageways 705, 707 to a discharge nozzle 711 provided with acheck valve 713 biased to closed position as by spring 714. This checkvalve is arranged to have a small leak when it is closed, as by burringits seat. Pump 703 is also connected via a branch passageway 709 to anactuating chamber 715 closed by a flexible diaphragm 717 held in placeby a suction head 719. Head 719 is hollow, forming a suction chamber 721connected to the suction line 722 and having a bleed aperture 723communicating to the ambient air through a filter 725. The outer end ofaperture 723 acts as a valve seat for a valve member 727 secured to andmovable with the diaphragm 717. -A spring 729 around the stem of thevalve member urges the diaphragm to the left away from head 719 and thusholds the valve member 727 closed against its seat under steadyconditions when the carburetor throttle 731 is not being moved. Thespring opposes the distributor-actuating suction supplied to chamber 721as well as the hydraulic pressure in chamber 715.

When the throttle is opened, a link 733 and lever 735 causes the pump703 to pump out gasoline, increasing the pressure in passageway 707until valve 713 is opened. This pressure increase also moves diaphragm717 to the right, opening the valve 727 and permitting air to bleed intothe suction line 722. Termination of the throttle opening movementpermits the pressure in passageway 709 to be relieved by way of thesmall leak in valve 713. This returns diaphragm 717 to its illustratedposition where it holds valve 727 closed, permitting the suction in line722 to reach its equilibrium value and appropriately advance theignition. Gasoline refills the accelerator pump by flowing from thecarburetor bowl through ball check valve 706, as the throttle moves inthe closing direction. The apparatus is accordingly always prepared foracceleration.

The ignition retarding of the present invention can also be effected byreplacing the normal vacuum advance mechanism 12 (FIG. 1) with aretarding mechanism and arranging for the ignition timing to otherwisebe in the fully advanced condition for most economical operation. Thebreaker plate which carries the cam follower for the breaker cam canstill be connected to a diaphragm control, but such connection isarranged to move the breaker plate in ignition-retarding direction inresponse to diaphragm-operating forces such as are available from aconvenient suction or pressure line. An acceleration-responsivemechanism such as any of those described in the foregoing constructionscan then be connected to cause the suction or pressure to operate thediaphragm and thus provide the ignition retarding when it is needed.

A still further arrangement pursuant to the present invention is tomount the usual distributor rotor cam on its shaft in such a way thatthe cam has its position retarded by accelerations. Instead of havingthe cam fixed on the shaft, it can in this arrangement be looselyrotatable with respect to the shaft, and held by a spring in the desiredcruise position, just as arm 317 of FIG. 4 is held. When the engineundergoes an acceleration the inertia of the cam causes it to compressthe holding spring enough to establish the desired retard. FIG. 4A showssuch an arrangement, the cam 367 being shown rotatably mounted withrespect to the distributor shaft 302.

FIG. 12 illustrates a modified form of the construction of FIG. 11 inwhich the vacuum advance is offset without significantly changing thedegree of vacuum in the vacuum advance line. In FIG. 12 the carburetor801 of essentially the same construction as carburetor 701, has adiaphragm 817 connected to similarly respond to pressure increases inthe acceleration pump discharge line. Diaphragm 817 is arranged tooperate a valve 827 which controls the application ofdistributor-advance vacuum from line 822 to line 824 and in this way toa retard chamber 836 where it opposes the ignition-advancing effect ofthe vacuum in line 822. A vacuum chamber 821 on car buretor 801communicates with vacuum line 822 and is closed by an auxiliarydiaphragm 828 also connected to valve 827. The space between diaphragms817 and 828 is divided by a partition 833 which has a seal 832 for thepassage of the valve actuator, and a vent as shown at 830 vents thespace between diaphragm 817 and the partition to make sure suctionchamber 821 is isolated from the gasoline on the bowl side of diaphragm817. A small external air leak 834 is shown in the outer wall of retardchamber 836 to slowly relieve the suction developed in that chamber andthus terminate the ignition-retarding action after valve 827 is closed.A bleed 839 can also be provided in diaphragm 828 to balance thepressures on both sides of this diaphragm so that valve-closing spring829 can be accurately calibrated.

When the throttle of carburetor 801 goes through movement in the openingdirection, its acceleration pump is operated causing diaphragm 817 tomove to the right as in the construction of FIG. 11. This opens valve827, causing the ignition-advancing vacuum to be applied to retardchamber 836, thus retarding the ignition. When the throttle-openingmovement is completed, diaphragm 817 returns from its righthanddeflection causing valve 827 to close and the suction in retard chamber836 is then dissipated by air coming in through leak 834. This permitsthe ignition to be advanced under the influence of the suction in line822.

When the ignition retarding of the present invention is arranged to takeplace during accelerations of at least about one mile per hour persecond, the emission of hydrocarbons in the exhaust is reduced about 23percent in the California emission tests. In one instance the reductionwas from 181 parts per million to 139 parts per million in a vehiclethat had already been equipped in accordance with FIG. 1 of the U.S.Pat. 3,310,045, granted Mar. 21, 1967, to have very low emission evenwithout the present invention.

The present invention also reduces nitrogen oxide emissions about 22percent. In the hot cycles of a typical California test the reductionwas from 1,517 parts per million to 1,185 parts per million in theabove-described engine.

The operation of an automobile with an engine having an ignition-timingarrangement in accordance with the present invention, is not perceptiblydifferent from that which is provided by the prior art type ofignition-timing arrangement. The retarding that is effected inaccordance with the present invention tends to reduce the engines torqueslightly but this is not noticed by the driver inasmuch as the throttleis being opened and this causes a net increase in torque. It is notnecessary to make any special provisions to take care of throttlemanipulations associated with the cranking and starting of an engine.Intake manifold suction does not reach any significant level until acranked engine begins to fire regularly, so that before such occurrencethe apparatuses of FIGS. 1, 2, 3, 5, 8 and 9 have no effect. Duringcranking the battery current supply to the electrically timedconstructions of FIGS. and 9 is so low that they will not begin tooperate or begin to operate well, and a small closing movement of thethrottle after the engine has started running will prevent the vacuumbleed otherwise associated with throttIe-opening movements of most ofthe constructions during the engine starting. The latching action in theconstruction of FIG. 9 will cause the apparatus to go through a vacuumbleed as a result of such throttle-opening movements.

There is a somewhat greater consumption of fuel caused by the presentinvention but since the mild accelerations during which the retarding ofthe invention takes place constitute only a relatively small portion ofthe total engine operation, the increase in consumption is generally notsignificant.

The bleeding into the vacuum line that effects spark advance is notlimited to being accomplished by opening the vacuum line directly orindirectly to the ambient air. The bleed opening can instead be made toother bleed sources such as the carburetor venturi or even to a highpressure air supply. A venturi-connected bleed is particularly desirablein that the bleed then varies with the air flow rate through thecarburetor. As a result the bleed rate diminishes as accelerationproceeds, and the net effect can be used to keep the controlled vacuumapproximately constant.

FIG. 13 illustrates the latter construction. A carburetor bore is hereshown at 901 and it is provided with a vacuum ad vance port 903 justabove the upper edge of throttle plate 931. The vacuum advance portcommunicates with the usual ignition advance suction head 912 and alsoby way of passageway 922, suction control valve 927, and passageways924, 926 to a restricted bleed port 928 in the throat venturi. VAlve 927is connected to and operated by a diaphragm 917 that defines a suctioncontrol chamber 921 and the valve is biased by a spring 929 toward openposition. This spring keeps the valve open so long as the vacuum inchamber 921 is weaker than that provided under cruise conditions. Whenundergoing a mild acceleration from such conditions port 903 iseffectively exposed to intake manifold vacuum and that vacuum becomesless intense, permitting valve 927 to open the bleed path. Because air'is now moving through the venturi the bleed is not as complete as theventing in the construction of FIG. 1 for example. The vacuum in line922 and in the suction advance head 912 might therefore drop to about 7inches of mercury for example. Most of the vacuum advance will still bedissipated and as the automobile accelerates air moves through thecarburetor venturi more and more rapidly, the effectiveness of the bleeddiminishes and the 7 inch level can be maintained with very little or novariations. The completion of the acceleration will carry the vacuum inline 922 to the normal level, causing diaphragm 917 to close bleed valve927. This restores the full vacuum advance along with its good fueleconomy and performance.

The bleed can also be arranged to reduce the vacuum intensity to otherpredetermined levels, even down to as little as 4 inches of mercury orless, at which low level all the normal vacuum advance is lost.

It is accordingly possible to have the construction of FIG. 13 adjustedto have its mild accelerationretard take place with the advance vacuumselected for best operation of the particular engine and automobile towhich it is fitted. Thus with an engine that is operated with very leanfuel mixtures, the mild acceleration retard preferably corresponds toonly about three-fourths of the vacuum advance or even less unless theengine is not expected to provide flashy performance.

The construction of FIG. 13 has its vacuum port 903 located so thatthere is no vacuum advance when the engine is idling, the advancecommencing as the throttle is opened. This construction is particularlydesirable for use with mild acceleration retarding since the ignitionsystem is not in full advance condition when an acceleration begins fromvery low speeds. Accordingly there is no delay required to bleedadvancing vacuum before the retarding commences. Also the bleedarrangement of the construction of FIG. 13 reduces its effectiveness asthe engine speed increases, and so for turnpike driving and the likethere is very little or no mild acceleration retarding. Such driving canaccordingly be carried out with maximum fuel economy and maximum engineperformance. On the other hand for city driving where nitrogen oxideconcentrations are most serious the bleeding of the construction of FIG.13 is fully effective.

The ignition retard by shifting of the breaker plate for example, canalso be effected by nonpneumatic means, as by an electromagnet connectedto move the plate into retard position in response to an electriccurrent sent through the magnet by an acceleration-responsive switch asin the constructions of FIGS. 5 and 9. This construction is shown inFIG. 14 which is a modification of FIG. 9 in which solenoid armature 521is directly connected to the breaker plate,

Another aspect of the present invention is the retarding of the ignitionduring decelerations of an automobile operated by a spark-ignitionengine. Retarding of the ignition at such times also reduces undesiredemissions and in addition improves the engine braking. For this type ofoperation the constructions of FIGS. 1, 5, 8, 9 and 10 can be modified(see FIG. 8) so that they cause bleeding in response to throttle-closingmovements rather than throttle-opening movements. Similarly theconstruction of FIGS. 3 and 4 can be reversed so that the bleeding itcauses takes place only during decelerations. Such decelerationretarding is particularly helpful when the throttling is arranged tokeep the engine firing during deceleration as by a throttle-closingcheck and/or increase of the idle mixture flow rate along the linesdescribed in US. Pat. No. 3,282,261 granted Nov. 1, 1966. With theincrease in idle mixture flow rate it is also desirable to keep theignition timing retarded during idle operation as by combining thedeceleration control with an idle control, as in the construction of thepresent FIG. 1, for example.

Obviously many other modifications and variations of the presentinvention are possible in the light of the above teachings. Within thescope of the appended claims the invention may accordingly be practicedotherwise than as specifically described.

What is claimed:

1. in an ignition timing mechanism that is vacuum-responsive andspeed-responsive and keeps the ignition timing of a spark-ignitionengine highly advanced during constant speed operation under part load,the improvement according to which supplemental timing control means isconnected to the timing mechanism to cause the ignition advance to beretarded at least about from said highly advanced condition for a fewseconds when the engine is operated to effect mild acceleration, saidsupplemental timing control means being essentially insensitive toinfluences other than accelerations.

2. The combination of claim 1 in which the supplemental timing controlmeans is connected to gradually apply and gradually terminate theignition retarding.

3. The combination of claim 1 in which the supplemental timing controlmeans is connected for operation by the inertia of a rotating portion ofthe engine.

4. The combination of claim 1 in which the ignition timing mechanism isfurther connected to cause the ignition advance to be retarded duringidling of the engine.

5. The combination of claim 1 in which the supplemental control includesterminating structure that terminates its relit tardin g action a fewseconds after that action starts.

6. In an ignition timing mechanism having a vacuumresponsive andspeed-responsive advance arrangement connected to advance the ignitiontiming of a spark-ignition engine by amounts that essentially providegood fuel economy, the improvement according to which engine-responsiveretard means is connected to the timing mechanism to temporarily offsetthe vacuum advance about l0 for a period of at least a few secondswhenever the engine is operated to effect mild acceleration.

7. In a spark ignition engine timing combination having a first timingmechanism that advancesthe ignition timing with increases in enginespeed and a second timing mechanism that advances the ignition timingwith decreases in pressure in the combustion mixture intake system, theimprovement according to which a third timing mechanism is connected tothe second timing mechanism and to the engine and has momentary controlmeans that offsets the timing action of the second timing mechanism foronly a few seconds whenever the engine is operated to effect mildacceleration.

8. The combination of claim 7 in which the third timing mechanism iselectrically timed.

9. The combination of claim 7 in which the third timing mechanism ispneumatically timed.

10. An ignition retard assembly for a spark ignition engine having acarburetor venturi, speed-responsive ignition advance means andintake-manifold-vacuum-responsive ignition advance means, said assemblyhaving a bleed connection for reducing the advance of the last-mentionedmeans, the bleed connection opening into the carburetor venturi so thatbleeding takes place from the venturi, and an acceleration-responsivecontrol connected to said bleed connection to open and close saidconnection in response to an acceleration.

11. The combination of claim 10 in which the assembly is connected tomaintain a substantially constant vacuum advance during a mildacceleration.

1. In an ignition timing mechanism that is vacuum-responsive andspeed-responsive and keeps the ignition timing of a sparkignition enginehighly advanced during constant speed operation under part load, theimprovement according to which supplemental timing control means isconnected to the timing mechanism to cause the ignition advance to beretarded at least about 10* from said highly advanced condition for afew seconds when the engine is operated to effect mild acceleration,said supplemental timing control means being essentially insensitive toinfluences other than accelerations.
 2. The combination of claim 1 inwhich the supplemental timing control means is connected to graduallyapply and gradually terminate the ignition retarding.
 3. The combinationof claim 1 in which the supplemental timing control means is connectedfor operation by the inertia of a rotating portion of the engine.
 4. Thecombination of claim 1 in which the ignition timing mechanism is furtherconnected to cause the ignition advance to be retarded during idling ofthe engine.
 5. The combination of claim 1 in which the supplementalcontrol includes terminating structure that terminates its retardingaction a few seconds after that action starts.
 6. In an ignition timingmechanism having a vacuum-responsive and speed-responsive advancearrangement connected to advance the ignition timing of a spark-ignitionengine by amounts that essentially provide good fuel economy, theimprovement according to which engine-responsive retard means isconnected to the timing mechanism to temporarily offset the vacuumadvance about 10* for a period of at least a few seconds whenever theengine is operated to effect mild acceleration.
 7. In a spark ignitionengine timing combination having a first timing mechanism that advancesthe ignition timing with increases in engine speed and a second timingmechanism that advances the ignition timing with decreases in pressurein the combustion mixture intake system, the improvement according towhich a third timing mechanism is connected to the second timingmechanism and to the engine and has momentary control means that offsetsthe timing action of the second timing mechanism for only a few secondswhenever the engine is operated to effect mild acceleration.
 8. Thecombination of claim 7 in which the third timing mechanism iselectrically timed.
 9. The combination of claim 7 in which the thirdtiming mechanism is pneumatically timed.
 10. An ignition retard assemblyfor a spark ignition engine having a carburetor venturi,speed-responsive ignition advance means andintake-manifold-vacuum-responsive ignition advance means, said assemblyhaving a bleed connection for reducing the advance of the last-mentionedmeans, the bleed connection opening into the carburetor venturi so thatbleeding takes place from the venturi, and an acceleration-responsivecontrol connected to said bleed connection to open and close saidconnection in reSponse to an acceleration.
 11. The combination of claim10 in which the assembly is connected to maintain a substantiallyconstant vacuum advance during a mild acceleration.